Heat-dissipating substrate and fabricating method thereof

ABSTRACT

Embodiments of the invention provide a heat-dissipating substrate and a fabricating method of the heat-dissipating substrate. According to various embodiments, the heat-dissipating substrate includes a plating layer divided by a first insulator formed in a division area. A metal plate is formed on an upper surface of the plating layer and filled with a second insulator at a position corresponding to the division area, with an anodized layer formed on a surface of the metal plate. A circuit layer is formed on the anodized layer which is formed on an upper surface of the metal plate. The heat-dissipating substrate and fabricating method thereof achieves thermal isolation by a first insulator formed in a division area and a second insulator.

RELATED APPLICATION

This application claims the benefit of and priority to U.S. patent application Ser. No. 12/614,407, entitled, “Heat-Dissipating Substrate and Fabricating Method Thereof,” filed on Nov. 7, 2009, which claims priority under 35 U.S.C. §119 to Korean Patent Application No. KR 10-2009-0086997, entitled, “Heat-Dissipating Substrate And Fabricating Method Of The Same,” filed on Sep. 15, 2009, which are all hereby incorporated by reference in their entirety into this application.

BACKGROUND

1. Field of the Invention

The present invention relates to a heat-dissipating substrate and a fabricating method thereof.

2. Description of the Related Art

Today, as electronic parts are seeking miniaturization, thinness, and high density and as such become light, thin, short and small, the miniaturization, micro patterning and packaging of a Printed Circuit Board (PCB) are being carried out with these things being taken into consideration. Thus, the PCB is more complicated in structure and the mounting density of parts is increased.

However, as the number and density of electronic parts mounted on the PCB increase, measures are required to provide for the dissipation of heat generated from the electronic parts and to prevent warpage.

In order to solve the problems presented by heat dissipation and warpage, a variety of types of package substrates have been proposed. However, the package substrate may be deformed because of residual stress resulting from a difference in a thermal expansion coefficient between a semiconductor chip, underfill and a substrate and a thermal cycle during a fabrication process. Thus, a structure for minimizing deformation using a metal core which is low in thermal expansion coefficient and for solving the problems of warpage and heat dissipation has been proposed.

FIGS. 1 to 5 are sectional views illustrating a conventional fabricating method of a PCB using a metal core. The fabricating method will be described with reference to the accompanying drawings.

First, a metal core 11 having high heat conductivity is prepared (see FIG. 1).

Next, through holes 12 are formed in the metal core 11 through drilling or etching (see FIG. 2).

Subsequently, insulating layers 13 are formed on both sides of the metal core 11 including the through holes 12 (see FIG. 3).

Next, for layer-by-layer connection, the through holes 12 of the metal core 11 are mechanically machined, thus forming via holes 14. Here, the holes 14 are machined to be smaller than the through holes 12 of the metal core 11 to be insulated from a copper plating layer formed on the inner wall of each via hole 14 through a subsequent copper plating process (see FIG. 4).

Thereafter, the copper plating layer is formed on the surface of each insulating layer 13 and the inner wall of each via hole 14 through chemical copper plating, that is, electroless plating and electrolytic plating. Through exposing, developing and etching processes, circuit layers 15 are formed. In this way, a PCB 10 is fabricated.

However, the conventional fabricating method of the metal core heat-dissipating substrate 10 has the following problems.

First, in order to prevent electric failure due to a short occurring in the plating layer formed on the metal core 11 and the inner wall of each via hole 14, the through holes 12 must be machined to a sufficient size. In this case, the ratio of the remaining metal core for a substrate area is only about 50%, so that heat conductivity is reduced.

In order to increase heat dissipation efficiency, the metal core 11 is inserted. However, this increases the overall thickness of the substrate. Since the insulating layer 13 such as a prepreg which is very low in heat conductivity is used, the heat conducting effect of the metal core is deteriorated.

In order to solve the problems, the structure of an anodized metal substrate 50 shown in FIG. 6 has been proposed. According to this structure, an anodized layer 54 is formed on a surface of the metal plate 52, and a circuit layer 56 is formed on the anodized layer 54.

The anodized metal substrate 50 is superior to the metal core heat-dissipating substrate 10 in heat dissipation performance. However, the anodized metal substrate 50 is problematic in that, when a device susceptible to heat is mounted on the circuit layer 56, heat conduction is performed and thermal isolation is not performed, so that the device susceptible to heat may be damaged.

SUMMARY

Accordingly, embodiments of the present invention have been made to provide a heat-dissipation substrate which enables thermal isolation and a method of fabricating the heat-dissipation substrate.

According to an embodiment of the present invention, there is provided a heat-dissipation substrate including a plating layer divided by a first insulator formed in a division area. A metal plate is formed on an upper surface of the plating layer and filled with a second insulator at a position corresponding to the division area, with an anodized layer formed on a surface of the metal plate. A circuit layer is formed on the anodized layer which is formed on an upper surface of the metal plate.

In accordance with an embodiment of the invention, the anodized layer formed on a lower surface of the metal plate is provided between the first insulator and the second insulator.

In accordance with an embodiment of the invention, the first insulator and the second insulator is formed to contact each other.

In accordance with an embodiment of the invention, the metal plate is made of aluminum or aluminum alloy, and the anodized layer may comprise an aluminum anodized layer.

In accordance with an embodiment of the invention, a groove is formed in the plating layer.

In accordance with an embodiment of the invention, the plating layer forms an open part therein to have a circuit pattern, and the circuit pattern is electrically connected to the circuit layer through a via hole which is formed through the metal plate.

In accordance with an embodiment of the invention, a through hole is formed in the metal plate, and the anodized layer is formed on the metal plate including an inner wall of the through hole, and the via hole is formed in the through hole to be connected to the circuit layer

In accordance with an embodiment of the invention, the open part is filled with a third insulator.

In accordance with an embodiment of the invention, there is provided a fabricating method of a heat-dissipating substrate, including the steps of (A) forming a plating layer, divided by a plating resist formed in a division area, on a first surface of a metal plate on which an anodized layer is formed, and (B) removing the plating resist from the division area, and filling the division area with a first insulator. The fabricating method further includes the steps of (C) forming a circuit layer on the anodized layer which is formed on a second surface of the metal plate, and (D) removing the metal plate from an upper portion of the division area, removing the anodized layer from the second surface of the metal plate, and filling removed parts with a second insulator.

In accordance with an embodiment of the invention, at (D), the anodized layer is removed from the first surface of the metal plate, and the second insulator is filled to contact the first insulator.

In accordance with an embodiment of the invention, the metal plate is made of aluminum or aluminum alloy, and the anodized layer includes an aluminum anodized layer.

In accordance with an embodiment of the invention, a groove is formed in the plating layer.

In accordance with an embodiment of the invention, the plating layer forms an open part therein to have a circuit pattern, and the circuit pattern is electrically connected to the circuit layer through a via hole which is formed through the metal plate.

In accordance with an embodiment of the invention, a through hole is formed in the metal plate, and the anodized layer is formed on the metal plate including an inner wall of the through hole, and the Via hole is formed in the through hole to be connected to the circuit layer.

In accordance with an embodiment of the invention, the open part is filled with a third insulator.

Various objects, advantages and features of the invention will become apparent from the following description of embodiments with reference to the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS

These and other features, aspects, and advantages of the invention are better understood with regard to the following Detailed Description, appended Claims, and accompanying Figures. It is to be noted, however, that the Figures illustrate only various embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it may include other effective embodiments as well.

FIGS. 1 to 5 are sectional views illustrating a conventional fabricating method of a PCB using a metal core.

FIG. 6 is a sectional view illustrating a conventional anodized metal substrate.

FIGS. 7A and 7B are a sectional view and a plan view illustrating a heat-dissipating substrate, in accordance with an embodiment of the invention.

FIG. 8 is a sectional view illustrating a heat-dissipating substrate, in accordance with an embodiment of the invention.

FIG. 9 is a sectional view illustrating a heal-dissipating substrate, in accordance with an embodiment of the invention.

FIG. 10 is a sectional view illustrating a heat-dissipating substrate, in accordance with an embodiment of the invention.

FIG. 11 is a sectional view illustrating a heat-dissipating substrate, in accordance with an embodiment of the invention.

FIGS. 12A and 12B through 16A and 16B are sectional views and plan views illustrating the fabricating method of the heat-dissipating substrate, in accordance with embodiments of the invention in sequence.

DETAILED DESCRIPTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, which illustrate embodiments of the invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the illustrated embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout. Prime notation, if used, indicates similar elements in alternative embodiments.

Structure of Heat-Dissipating Substrate—First Embodiment

FIGS. 7A and 7B are a sectional view and a plan view illustrating a heat-dissipating substrate according to a preferred first embodiment of the present invention. Hereinafter, a heat-dissipating substrate 100 a according to this embodiment will be described with reference to the drawings.

As shown in FIGS. 7A and 7B, the heat-dissipating substrate 100 a according to this embodiment has an anodized metal substrate which is provided on the upper surface of a plating layer 108 divided by a first insulator 110 and is divided by a second insulator 114 formed at a position corresponding to that of the first insulator 110.

The plating layer 108 is formed on the lower surface of the anodized metal substrate and is divided by the first insulator 110 which is provided in the plating layer 108 to form a division area. In detail, the plating layer 108 formed inside the first insulator 110 is thermally isolated from the plating layer 108 formed outside the first insulator 110 by the first insulator 110. Here, the first insulator 110 is an insulating material having low heat conductivity, and serves to prevent thermal flow between plating layers 108.

The anodized metal substrate is configured such that an anodized layer 104 is formed on a surface of a metal plate 102 and a circuit layer 112 is formed on the anodized layer 104. The second insulator 114 is formed in the metal plate 102 at a position corresponding to that of the first insulator 110, so that the metal plate 102 is divided. In detail, the metal plate 102 positioned above the first insulator 110 and the anodized layer 104 formed on the upper surface of the metal plate 102 are eliminated. The eliminated portion is filled with the second insulator 114, so that the circuit layer 112 and the metal plate 102 provided inside the second insulator 114 are thermally isolated from the circuit layer 112 and the metal plate 102 provided outside the second insulator 114. That is, when electronic devices are mounted on the circuit layer 112, a device resistant to heat and a device susceptible to heat may be separately provided inside and outside the second insulator 114. According to this embodiment, the anodized layer 104 is provided between the first insulator 110 and the second insulator 114.

Structure of Heat-Dissipating Substrate—Second Embodiment

FIG. 8 is a sectional view illustrating a heat-dissipating substrate according to a preferred second embodiment of the present invention. Components common to both the embodiments will carry the same reference numerals.

As shown in FIG. 8, a heat-dissipating substrate 100 b according to this embodiment is different from the heat-dissipating substrate 100 a according to the first embodiment in that the anodized layer 104 between the first insulator 110 and the second insulator 114 is eliminated, so that the first insulator 110 is in contact with the second insulator 114. Since other parts of the second embodiment are equal to those of the first embodiment except for the above-mentioned difference, the duplicate description will be omitted herein.

According to this embodiment, the anodized layer 104 having the relatively high heat transfer characteristics of about 10 to 30 W/mK is removed from the division area and the second insulator 114 having low heat conductivity is filled. Such a structure achieves a higher thermal isolating function in comparison with the former embodiment.

Structure of Heat-Dissipating Substrate—Third Embodiment

FIG. 9 is a sectional view illustrating a heat-dissipating substrate according to a preferred third embodiment of the present invention. Components common to the embodiments will carry the same reference numerals.

As shown in FIG. 9, a heat-dissipating substrate 100 c according to this embodiment is different from the heat-dissipating substrate 100 a according to the first embodiment in that grooves 108 a are formed in a plating layer 108, so that the plating layer 108 has the structure of a radiative fin, thus improving heat dissipating performance. That is, the grooves 108 a are formed in the plating layer 108 to increase a surface area, so that heat dissipating performance is superior to that of the first embodiment.

Meanwhile, the formation of the grooves 108 a in the plating layer 108 of the heat-dissipating substrate 100 b according to the second embodiment falls within the scope of the present invention.

Structure of Heat-Dissipating Substrate—Fourth Embodiment

FIG. 10 is a sectional view illustrating a heat-dissipating substrate according to a preferred fourth embodiment of the present invention. Components common to the embodiments will carry the same reference numerals and the duplicate description will be omitted herein.

As shown in FIG. 10, a heat-dissipating substrate 100 d according to this embodiment is constructed so that an open part 108 b is formed in a plating layer 108 to form a circuit pattern, and a circuit layer 112 having a via hole 112 a which is electrically connected to the plating layer 108 and a pattern part 112 b is formed on a metal plate 102.

That is, according to this embodiment, the plating layer 108 is patterned to form the circuit pattern, thus realizing a structure wherein circuit layers are formed on both sides of the metal plate 102. Here, the plating layer 108 serves as both the circuit pattern and the heat dissipating member.

Structure of Heat-Dissipating Substrate—Fifth Embodiment

FIG. 11 is a sectional view illustrating a heat-dissipating substrate according to a preferred fifth embodiment of the present invention. Components common to the embodiments will carry the same reference numerals and the duplicate description will be omitted herein.

As shown in FIG. 11, a heat-dissipating substrate 100 e according to this embodiment is constructed so that an open part 108 b is filled with a third insulator 108 c so as to improve the reliability of the heat-dissipating substrate 100 d according to the fourth embodiment. Since other parts of the fifth embodiment are equal to those of the fourth embodiment except for the above-mentioned difference, the duplicate description will be omitted herein.

Fabricating Method of Heat-Dissipating Substrate

FIGS. 12A and 12B through 16A and 16B are sectional views and plan views illustrating the fabricating method of the heat-dissipating substrate according to a preferred embodiment of the present invention in sequence. Hereinafter, the fabricating method of the heat-dissipating substrate according to this embodiment will be described with reference to the accompanying drawings.

First, as shown in FIGS. 12A and 12B, the anodized layer 104 is formed on the surface of the metal plate 102.

Here, a metal material which is relatively cheap and easily obtained and aluminum (Al) or aluminum alloy having very superior heat transfer characteristics may be used as the metal plate 102. Since the metal plate 102 has superior heat transfer characteristics, the metal plate 102 serves as a heat dissipating member.

For example, the anodized layer 104 is made by putting the metal plate 102 made of aluminum or aluminum alloy into an electrolyte such as boric acid, phosphoric acid, sulfuric acid, or chromic acid, applying the anode to the metal plate 102 and applying the cathode to the electrolyte. At this time, an aluminum anodized film (Al₂O₃) having the relatively high heat transfer characteristics of about 10 to 30 W/mK is formed on a surface of the metal plate 102. Since the anodized layer 104 has an insulating function, it is possible to form the circuit layer on the anodized layer 104. Further, the anodized layer 104 is formed to be thinner than a resin insulating layer and has high heat transfer characteristics, thus contributing to the thinness and heat dissipating performance of the heat-dissipating substrate.

Next, as shown in FIGS. 13A and 13B, after a plating resist 106 is applied to a division area A on one surface of the metal plate 102 on which the anodized layer 104 is formed, the plating layer 108 is formed everywhere except for on the division area A. Here, the plating layer 108 is divided into an inner plating layer and an outer plating layer by the division area A. The plating resist 106 formed in the division area A thermally isolates the inner plating layer from the outer plating layer.

In detail, the plating resist 106 such as a dry film or a positive liquid photo resist (P-LPR) is applied to the anodized layer 104 which is formed on a surface of the metal plate 102. Subsequently, ultraviolet rays are exposed to a portion of the plating resist 106 other than the division area A, the exposed portion is removed using a developing solution, and the resist removed portion goes through an electroless plating process or an electrolytic plating process, thus forming the plating layer 108.

Next, as shown in FIGS. 14A and 14B, the plating resist 106 is removed from the division area A, and the division area A is filled with the first insulator 110 having low heat conductivity.

Here, the plating resist 106 is removed using a stripper such as sodium hydroxide (NaOH) or potassium hydroxide (KOH).

Meanwhile, if the heat conductivity of the plating resist 106 is low, it may substitute for the first insulator 110. Thus, this process may be omitted.

Next, as shown in FIGS. 15A and 15B, the circuit layer 112 is formed on the anodized layer 104 which is formed on the other surface of the metal plate 102.

The circuit layer 112 is formed by forming the plating layer using an electroless plating process or an electrolytic plating process, and patterning the plating layer.

Preferably, the circuit layer 112 is not formed on the division area A filled with the second insulator 114 for thermal isolation.

Finally, as shown in FIGS. 16A and 16B, the anodized layer 104 and the metal plate 102 of the division area A are removed, and a removed portion is filled with the second insulator 114.

The anodized layer 104 may be removed by laser beam, and the metal plate 102 may be removed through an etching process.

In this step of the process, the metal plate 102 of the division area A and the anodized layer 104 formed on the upper surface of the metal plate 102 are removed.

Through the fabrication process, the heat-dissipating substrate 100 a of FIG. 7 is obtained.

Hereinbefore, the fabricating method of the heat-dissipating substrate according to the first of the present invention has been described. However, it is apparent that the heat-dissipating substrates according to the second to fifth embodiments may be fabricated through the above-mentioned method, and so this falls within the scope of the present invention.

As described above, the present invention provides a heat-dissipating substrate and a fabricating method thereof, in which the division area of an anodized metal substrate is filled with an insulator to form a thermal isolation structure, thus permitting thermal isolation when a device resistant to heat and a device susceptible to heat are simultaneously mounted.

Embodiments of the present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.

The terms and words used in the present specification and claims should not be interpreted as being limited to typical meanings or dictionary definitions, but should be interpreted as having meanings and concepts relevant to the technical scope of the present invention based on the rule according to which an inventor can appropriately define the concept of the term to describe the best method he or she knows for carrying out the invention.

As used herein, terms such as “first” and “second” are arbitrarily assigned and are merely intended to differentiate between two or more components of an apparatus. It is to be understood that the words “first” and “second” serve no other purpose and are not part of the name or description of the component, nor do they necessarily define a relative location or position of the component. Furthermore, it is to be understood that the mere use of the term “first” and “second” does not require that there be any “third” component, although that possibility is contemplated under the scope of the embodiments of the present invention.

The singular forms “a,” “an,” and “the” include plural referents, unless the context clearly dictates otherwise.

As used herein and in the appended claims, the words “comprise,” “has,” and “include” and all grammatical variations thereof are each intended to have an open, non-limiting meaning that does not exclude additional elements or steps.

Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.

Although the present invention has been described in detail, it should be understood that various changes, substitutions, and alterations can be made hereupon without departing from the principle and scope of the invention. Accordingly, the scope of the present invention should be determined by the following claims and their appropriate legal equivalents. 

What is claimed is:
 1. A fabricating method of a heat-dissipating substrate, comprising: (A) forming a plating layer, divided by a plating resist formed in a division area, on a first surface of a metal plate on which an anodized layer is formed; (B) removing the plating resist from the division area, and filling the division area with a first insulator; (C) forming a circuit layer on the anodized layer which is formed on a second surface of the metal plate; and (D) removing the metal plate from an upper portion of the division area, removing the anodized layer from the second surface of the metal plate, and filling removed parts with a second insulator.
 2. The fabricating method as set forth in claim 1, wherein, at (D), the anodized layer is removed from the first surface of the metal plate, and the second insulator is filled to contact the first insulator.
 3. The fabricating method as set forth in claim 1, wherein the metal plate is made of aluminum or aluminum alloy, and the anodized layer comprises an aluminum anodized layer.
 4. The fabricating method as set forth in claim 1, wherein a groove is formed in the plating layer.
 5. The fabricating method as set forth in claim 1, wherein the plating layer forms an open part therein to have a circuit pattern, and the circuit pattern is electrically connected to the circuit layer through a via hole which is formed through the metal plate.
 6. The fabricating method as set forth in claim 5, wherein a through hole is formed in the metal plate, and the anodized layer is formed on the metal plate including an inner wall of the through hole, and the via hole is formed in the through hole to be connected to the circuit layer.
 7. The fabricating method as set forth in claim 5, wherein the open part is filled with a third insulator. 